Biomedical subjects

M Gottlieb

Publications and source records attributed to M Gottlieb.

At least 55 records · Page 3Linked to original sources

PubMed1991

Phase I study of safety and pharmacokinetics of a human anticytomegalovirus monoclonal antibody in allogeneic bone marrow transplant recipients.

This study examined the safety and pharmacokinetic profile of a potentially therapeutic and fully human anti-CMV monoclonal antibody (SDZ MSL-109) in a phase I dose escalation trial in patients receiving allogeneic bone marrow transplants. Fifteen adult marrow transplant patients, twelve with chronic myelogenous leukemia and three with acute nonlymphocytic leukemia, in cohorts of five patients each, were administered monoclonal antibody intravenously at doses of 50, 250, and 500 micrograms/kg at approximately three-week intervals for six months. Administration of the monoclonal antibody was associated with minimal side effects and no dose-related toxicity. Antibody elimination curves in all dose groups were consistent with a two-compartment model with an alpha half-life at the low, middle, and high dose groups of 1.03, 0.82, and 0.79 days, and a beta half life of 13.9, 14.0, and 16.5 days, respectively. The volume of distribution decreased with repetitive dosing to approximate the plasma volume in each patient and the pharmacokinetic profile was comparable to that of human IgG. There was no host antiidiotypic or antiallotypic antibody formation, indicating that MSL-109 was not immunogenic. Further studies are warranted to assess the potential efficacy of human monoclonal anti-CMV disease in marrow transplant recipients and other patients with immunodeficiency disorders.

Adult↗

PubMed1991

Allogeneic bone marrow transplantation for relapsed and refractory lymphoma using genotypically HLA-identical and alternative donors.

Twenty-two patients, ages 16.6 to 43.9 years (median age, 30 years), with relapsed or refractory lymphoma were treated by allogeneic bone marrow transplantation after high-dose chemotherapy with or without total body irradiation (TBI). Seven patients had Hodgkin's disease, four had low-grade histology non-Hodgkin's lymphoma (NHL), seven had intermediate-grade NHL, and four had high-grade NHL. Of the 22 patients, 17 received T-cell (CD-3)-depleted marrow after intensive pretransplant chemoradiotherapy, and five received T-cell-replete grafts after chemotherapy-based preparative regimens. Five patients were transplanted from donors other than genotypically HLA-identical siblings: four from partially HLA-matched relatives, and one from a phenotypically HLA-identical unrelated donor. Acute graft-versus-host disease (GVHD) was less than or equal to grade II in all patients, and chronic GVHD was limited or absent in all but one patient. Of the 21 assessable patients, 17 (80.9%) achieved complete remissions. Death due to transplant-associated complications occurred in five patients, and five patients have relapsed. Thirteen patients are alive, and 12 are continuously relapse-free at a median follow-up of longer than 28 months (range, greater than 10 to greater than 58 months) from transplant. The cumulative probability of treatment failure from relapse or progression of lymphoma was 29% (95% confidence interval [CI], 12% to 51%), while the actuarial lymphoma-free (ie, event-free) survival plateau is 54.6% (95% CI, 34% to 76%). For young patients with advanced malignant lymphoma, allogeneic bone marrow transplantation appears superior to salvage chemotherapy for achievement of long-term, lymphoma-free survival and may be preferable to autologous bone marrow transplantation for selected patients.

Actuarial Analysis↗

PubMed1991

The influence of mechanical injury on the metabolic activity of transplanted cerebral cortex.

The authors studied the metabolic activity of rat embryonic cerebral cortex grafts (ED 15-16) implanted into rat brains immediately (TR0) and 14 days (TR14) after cavity formation. Over a period of two months, the ATP, lactate and glucose concentration in TR0 transplants remained at the same level as observed in the intact cortex, whereas in TR14 transplants the ATP and glucose concentration fell significantly and the lactate concentration rose. The DNA concentration rose in both types of transplants, but the increase was more pronounced in TR0 grafts. Choline acetyltransferase activity (a neuron marker) fell significantly in both cases, but the decrease was greater in TR14 transplants. The results indicate that grafts implanted into the brain immediately after cavities had been formed have better metabolic activity and are capable of longer survival than grafts implanted 14 days after cavitation.

Acetylcholine↗

PubMed1990

Risk factors for postvitrectomy fibrin formation.

We prospectively studied 194 patients undergoing vitrectomy between July 1988 and April 1989 to determine the incidence of postvitrectomy intraocular fibrin formation and the association of a variety of preoperative and intraoperative variables with the formation of severe postvitrectomy fibrin. Overall, 62 (32%) patients developed postvitrectomy fibrin; 25 (13%) had mild fibrin formation, 13 (6.5%) had moderate fibrin formation, and 24 (12.4%) had severe fibrin formation. By logistic multivariate analysis, preoperative factors that were independently predictive of severe fibrin formation included severe flare (P = .004), the presence of a previously placed scleral buckle (P = .001), and poor preoperative visual acuity (P = .007). Anterior epiretinal membrane dissection was the only intraoperative factor that was independently associated with an increased fibrin risk (P = .0003). A risk score derived from the multivariate analysis effectively categorized patients according to their likelihood of developing severe postvitrectomy fibrin. Results of this study may be useful in designing prophylactic interventions to decrease postvitrectomy fibrin formation.

Adult↗

PubMed1990

An inducible 3'-nucleotidase/nuclease from the trypanosomatid Crithidia luciliae. Purification and characterization.

Several species of protozoan parasites of the family Trypanosomatidae have a surface membrane-associated enzyme which is capable of hydrolyzing extracellular 3'-nucleotides and nucleic acids, thereby aiding in the acquisition of nutritionally required purines and Pi from their hosts. In Crithidia luciliae, this 3'-nucleotidase/nuclease previously has been shown to be highly regulated as purine and/or Pi starvation of this trypanosomatid leads to as much as a 1000-fold increase in enzyme activity. We have purified the enzyme to apparent homogeneity from detergent extracts of purine-starved C. luciliae by heparin-agarose chromatography followed by Mono Q and Mono S fast protein liquid chromatography. The enzyme had an apparent molecular weight of 43,000 and a pI of approximately 5.8. The enzyme displayed broad pH optima, with peaks at 8.0, for both nucleotidase and nuclease activities. The pH optima shifted to lower values when the activity was assayed in the presence of sulfhydryl reagents. The enzyme was most active with 3'-AMP and poly(A) in nucleotidase and nuclease assays, respectively. As a nuclease the enzyme hydrolyzed RNA at a faster rate than single-stranded DNA with no detectable hydrolysis of double-stranded DNA. The loss of enzyme activity which occurred upon storage at acid pH was prevented by the inclusion of Zn2+ in storage buffers. The physicochemical and kinetic properties of this trypanosomatid enzyme suggest that it is similar to the class I nucleases found in fungi and in germinating seedlings of higher plants.

Animals↗

PubMed1990

Crithidia luciliae: starvation for purines and/or phosphate leads to the enhanced surface expression of a protein responsible for 3'-nucleotidase/nuclease activity.

It has been shown previously that starvation of the trypanosomatid protozoan Crithidia luciliae for purines and/or inorganic phosphate results in increased levels of a surface membrane-associated 3'-nucleotidase/nuclease (3'-N'ase) activity which hydrolyzes both 3'-ribonucleotides and nucleic acids, thereby permitting the organisms to transport these essential nutrients across their cell membranes. A polypeptide with the requisite catalytic properties has been identified by an in situ gel activity assay following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In current studies, differential synthesis of the protein responsible for the 3'-N'ase activity was not demonstrable by comparisons of SDS-PAGE patterns of nutrient-replete or purine-starved parasites metabolically labeled with either [35S]methionine, [3H]leucine, or [3H]tyrosine. However, surface labeling of nutrient-replete and purine-starved cells revealed the enhanced expression of an 125I surface-labeled 43-kDa protein which comigrated with the 3'-N'ase activity in one- and two-dimensional electrophoretic systems. The amount of this surface-labeled peptide correlated with the level of 3'-N'ase activity as measured by test tube assay. Refeeding adenosine to purine-starved cells led to the loss of both the enzyme activity and the surface iodinatable 43-kDa band as a result of renewed cell division. Starvation of these organisms for phosphate also led to the enhanced expression of the 43-kDa radioiodinatable band. The results indicated that the 3'-N'ase protein, itself, is differentially expressed at the cell surface under conditions which lead to increased enzyme activity.

Animals↗

PubMed1990

Leishmania donovani: regulated changes in the level of expression of the surface 3'-nucleotidase/nuclease.

Leishmania donovani promastigotes have previously been shown to possess a surface membrane bound 3'-nucleotidase/nuclease (3'-N'ase) capable of hydrolyzing both nucleic acids and 3'-ribonucleotides. The specific activity of the 3'-N'ase was increased following transfer of the parasites to fresh, nutrient-replete media or to media lacking purines and/or inorganic phosphate (Pi). In nutrient-replete media, the enzyme activity was transiently elevated during the lag and early logarithmic phases of the growth curve; enzyme activity fell as the cells continued into late log and stationary phases. Purine- and Pi-starved cells exhibited significantly greater levels of 3'-N'ase activity than nutrient-replete cells. These levels remained elevated as long as the organisms were maintained in the deficient media. Nutrient-replete and purine-starved 125I surface-labeled parasites displayed differences in electrophoretic patterns. Upon purine starvation, incorporation of radiolabel was increased in proteins which migrated with apparent molecular weights of 70, 43, and 40 kDa. Comigration, in both one- and two-dimensional systems, of 3'-N'ase activity with the radiolabeled 43-kDa band demonstrated that this band was the catalytically active protein. Peptide mapping of the 70-, 43-, and 40-kDa proteins failed to demonstrate similarities in peptide sequence consistent with either a degradation or a precursor/product relationship. Treatment of the 43- and 40-kDa peptides with N-Glycanase indicated that they were differentially glycosylated. The cumulative results of these studies indicated that L. donovani can respond to altered culture conditions by the differential expression of surface proteins. In particular, the differential expression of the protein responsible for 3'-N'ase activity is consistent with the role of this enzyme in purine acquisition.

Animals↗

PubMed1990

Alterations in Leishmania donovani 3'-nucleotidase/nuclease activity banding pattern in polyacrylamide gels.

1. In the absence of protease inhibitors, partial purification of the 3'-nucleotidase/nuclease (3'-N'ase) from detergent extracts of Leishmania donovani leads to the appearance of bands, at 42,000 and 38,000 Da, of enzyme activity which, in SDS-PAGE, migrate faster than 43,000 Da, the apparent weight of the intact polypeptide. 2. The generation of these faster migrating species is a consequence of detergent extraction and is prevented by the addition of the protease inhibitors PMSF and leupeptin, suggesting that degradation by an endogenous protease is responsible. 3. Treatment of leishmanial membranes with exogenous proteases yields activity at 38,000 Da which is membrane-associated. Protease treatment has no effect on living cells. 4. The observed changes in enzyme migration are discussed in terms of enzyme stability and regulation. 5. The advantages and limitations of the in situ gel activity assay are considered.

Animals↗

PubMed1989

The surface membrane 3'-nucleotidase/nuclease of trypanosomatid protozoa.

The plasma membrane of protozoan parasites has been the subject of intense research interest because it serves as the interface between the parasite and its host] This structure functions in the acquisition of nutrients, in the response to environmental signals, in the secretion and excretion of metabolites, in the recognition of host surfaces and in the avoidance of host-destructive factors including the components of the immune response. Recent technological advances, such as the use of monoclonal antibodies and recombinant DNA methodologies, have led to the identification of specific plasma membrane components and their coding; sequences, often in the absence of information regarding the physiological role of the component. In this article Michael Gottlieb considers the functional activity of o plasma membrane enzyme which has been identified in a number of protozoa belonging to the family Trypanosomatidae, and considers its adaptive significance and possible evolution in the different genera of this family.

Journal Article↗

PubMed1989

Muscle glycogen depletion patterns during draught work in Standardbred horses.

Muscle fibre recruitment was investigated during draught loaded exercise by studying glycogen depletion patterns from histochemical stains of muscle biopsies from the gluteus and semitendinosus muscles. Three Standardbred trotters performed several intervals of draught loaded exercise on a treadmill with 34 kp at a trot (7 m/sec) and with 34 and 80 kp, respectively at a walk (2m/sec). Exercise was continued until the horses were unwilling to continue. Glycogen depletion was seen in all three fibre types when trotting with 34 kp for 5 or 10 mins. When an equal weight resistance was pulled at a walk, glycogen depletion was first seen in type I fibres only, then followed by a small percentage of type IIA fibres after at least 1 h. When 80 kp was pulled at a walk both type I and IIA fibres showed glycogen depletion, and after at least 30 mins exercise a small percentage of type IIB fibres was also depleted. These results indicate that the muscle fibres are depleted, in order, from type I through IIA to IIB as the intensity or duration of draught work increases.

Animals↗

PubMed1989

Effects of a draft-loaded interval-training program on skeletal muscle in the horse.

Five Standardbred trotters were trained on a treadmill 3 times/wk for 12 wk by intervals of draft-loaded exercise. The draft load was 34 kp and the velocity approximately 7 m/s. Muscle biopsies were taken from the gluteus medius and longissimus muscles before training and after 2, 4, 8, and 12 wk of training and from the brachiocephalicus muscle before and after training. Both the percentage and the area of type IIa fibers increased and the percentage of type IIb fibers decreased in the gluteus medius muscle during the first 2 wk of training, and then no further significant difference was noted. The percentage of type I fibers increased in the brachiocephalicus muscle, and the area of type IIb fibers increased in the longissimus muscle. The citrate synthase activity increased in the gluteus muscle only, and the increase was seen during the first 2 wk. No significant differences were seen in 3-hydroxy-acyl-CoA dehydrogenase and lactate dehydrogenase activities in the muscles during the entire training period. Less glycogen was utilized in the gluteus muscle and less blood lactate accumulated when the horses performed an unloaded submaximal exercise test after compared with before training. It can be concluded that rapid changes are induced in the gluteus medius muscle when horses are trained pulling a light-draft resistance at a submaximal trotting speed.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1989

Blood and muscle metabolic responses to draught work of varying intensity and duration in horses.

Three standardbred trotters performed treadmill exercise at a velocity of 2 m s-1 with a draught load of both 34 kiloponds (kp) (test 1) and 80 kp (test 2), and also at 7 m s-1 with 34 kp (test 3). The heart rate increased to average values of 111 (+/- 5), 157 (+/- 10) and 197 (+/- 7) beats min-1 in tests 1, 2, and 3, respectively. Plasma free fatty acids increased only during tests 1 and 2. Blood lactate and muscle glucose-6-phosphate and lactate concentrations were low after tests 1 and 2, but high after test 3, where also muscle glycogen utilisation was greatest. Muscle creatine phosphate and adenosine triphosphate concentrations decreased after test 3 only. The study indicates that oxidative metabolism is most important for energy supply in muscles when exercise is performed with draught loads of both 34 and 80 kp at a low velocity. Glycogenolysis with lactate accumulation and phosphagen breakdown becomes much more important when, with a draught load of 34 kp, the velocity of exercise increases.

Adenosine Triphosphate↗

PubMed1988

Crithidia luciliae: factors affecting the expression of 3'-nucleotidase/nuclease activity.

Crithidia luciliae, a trypanosomatid protozoan readily grown in axenic cultures, was shown to possess low levels of a surface membrane-bound ectoenzyme capable of hydrolyzing both 3'-ribonucleotides and nucleic acids. The specific activities of this 3'-nucleotidase/nuclease, with both mononucleotide and nucleic acid substrates, were greatly enhanced when the protozoa were deprived of purines, an essential nutrient. The catalytic activities were exhibited by a polypeptide which migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an Mr of 47,000. Starvation of these cells for inorganic phosphate (Pi), in media with or without purines, also led to an increase in the specific activity of the ectoenzyme compared to that of Pi- and purine-replete cells. In contrast, the level of enzyme activity was not increased when the protozoa were starved, under purine-replete conditions, for either arginine or hemin, two other essential nutrients. Cells starved simultaneously for either of the latter two nutrients and for purines also did not show increased levels of the 3'-nucleotidase/nuclease. The activation of the enzyme was also prevented by sodium arsenite, cycloheximide, actinomycin D, and tunicamycin indicating that the activation presumably required metabolic energy as well as new transcription, translation, and protein modification. The results demonstrate that the control of 3'-nucleotidase/nuclease expression is a regulated, adaptive response to growth-limiting levels of essential nutrients.

Adenosine↗

PubMed1988

Leishmania donovani: identification of glycoproteins released by promastigotes during growth in vitro.

Culture supernatants of metabolically labeled Leishmania donovani promastigotes were shown to contain approximately 40 electrophoretically distinct released protein compounds. Of these, approximately 20 were glycoproteins which contained terminal mannose residues, as judged by their specific binding to concanavalin A-agarose beads. Smaller subsets of the released glycoproteins were bound by agarose-conjugated Lens culinaris, Ricinus communis, and peanut lectins. Promastigote mannose-containing released glycoproteins were isolated by concanavalin A affinity chromatography and used to immunize a rabbit. This antiserum recognized the parasite-released mannose-containing glycoproteins, including the soluble acid phosphatase, both by immunoprecipitation from solution and in immunoblot analyses. In an antibody bridged enzyme assay this polyspecific serum was also capable of binding native acid phosphatase out of solution and bridging it to the denatured enzyme on SDS-PAGE transblots. Although this antiserum was raised against all 20 released glycoproteins, in agarose gels its major precipitin activity was against the secreted soluble acid phosphatase.

Acid Phosphatase↗

PubMed1988

Circulatory and muscle metabolic responses to draught work compared to increasing trotting velocities.

Circulatory and muscle metabolic responses were studied in 10 horses which all performed incremental draught work at a low trotting speed on a treadmill (D-test) and also exercise with gradually increasing velocities (S-test). Exercise was continued until the horses could no longer maintain the weights above the floor or maintain speed trotting without changing gait to a gallop. Muscle biopsies were taken from the gluteus and the semitendinosus muscles before, and immediately after, exercise. The heart rate (HR) increased linearly with both increasing draught resistance and velocity and reached mean values of 212 and 203 beats/min, respectively. Blood lactate levels increased exponentially to mean values of 12.9 and 7.9 mmol/litre in the two tests. Both HR and blood lactate levels were significantly higher at the cessation of work in the D-test compared to the S-test. The relationship between HR and blood lactate response in the S-test was similar to that in the D-test. The red cell volume was determined after a standardised exercise tolerance test and was significantly correlated both to the weightloading and to the velocity, producing a HR of 200 beats/min. The changes seen in muscle glycogen and glucose-6-phosphate were similar in the two tests, whereas significantly higher lactate levels and lower creatine phosphate and adenosine triphosphate levels were seen in the D-test compared to the S-test. It was concluded that high oxidative capacity is of importance both for fast trotting and for draught work.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1987

Silver staining of native and denatured eucaryotic DNA in agarose gels.

A modified method of silver staining for native and denatured eucaryotic DNA in 1% agarose gel is described. This method is at least fivefold more sensitive than ethidium bromide staining, with a detection limit of 2.5 ng for total DNA. The calibration curve is linear within the range 5-30 ng of single-stranded and double-stranded DNA. This method is especially advantageous for electrophoretic assessment of DNA molecular weights.

Animals↗

PubMed1987

Effect of tunicamycin on the extracellular acid phosphatase of Leishmania donovani promastigotes.

Inhibition of replication of Leishmania donovani promastigotes in axenic culture medium by tunicamycin, an inhibitor of asparagine linked protein glycosylation, depends upon the cell density of the culture at the time of addition of tunicamycin as well as upon the concentration of tunicamycin itself. Parasite multiplication in cultures with initial densities of less than or equal to 1 X 10(6) cells ml-1 and a tunicamycin concentration of 1 microgram ml-1 was limited to 2-3 replications, but this limitation was not observed in cultures with initial densities greater than or equal to 2 X 10(6) cells ml-1. Under conditions in which tunicamycin inhibited parasite growth and protein synthesis by only 15% and 6%, respectively, there was a greater than 90% reduction in the level of secreted acid phosphatase activity in comparison to control cultures. The extracellular acid phosphatase activity remaining in tunicamycin treated cultures was electrophoretically distinct from that found in control cultures. No significant decrease in the amount of [35S]methionine incorporated into acid insoluble products in the supernatant of tunicamycin treated cultures was observed, and a radiolabeled protein with an electrophoretic Mr of 97,000 was immunoprecipitated from this supernatant by an anti extracellular acid phosphatase antiserum. It was concluded that the L. donovani extracellular acid phosphatase, previously shown to be a mannose containing glycoprotein, contains N-linked oligosaccharides which are necessary for maintenance of its catalytic activity, but not its secretion.

Acid Phosphatase↗

PubMed1987

Alterations in cytotoxic and phenotypic subsets of natural killer cells in acquired immune deficiency syndrome (AIDS).

Testing of cytotoxic function using a panel of natural killer (NK)-sensitive target cells, including a unique herpes simplex virus-infected Raji-cell target, was performed in conjunction with phenotypic cell analysis by dual-color flow cytometry to characterize the NK system. Subjects included in the study were at risk for or infected with the etiologic agent of the acquired immune deficiency syndrome (AIDS), human immunodeficiency virus (HIV). A generalized defect in NK function was temporally correlated with disease manifestations, as evidenced by deficient NK lytic function in patients with AIDS and AIDS-related complex (ARC). Healthy at-risk subjects, including those seropositive for HIV, exhibited robust NK-cell function. Phenotypic analysis revealed that normal proportions of the NK-associated CD16+ (Leu11) Leu7- and CD16+(Leu11)Leu7+ lymphocyte subsets were maintained throughout the clinical progression of HIV infection. However, the proportion and numbers of cells of the CD8+(Leu2)Leu7+ subset were increased in AIDS, ARC, and healthy at-risk subjects, including those seronegative for HIV. These results are consistent with a qualitative defect in the NK system in AIDS, perhaps secondary to CD4-cell depletion and a concomitant lack of essential accessory factors. The elevation in CD8+(Leu2)/Leu7+ cells is not solely the result of HIV infection and may be a general response to viruses and/or other antigenic stimulation.

AIDS-Related Complex↗